극성 변환 전압을 이용한 전기화학 박리 그래핀의 품질 개선
Improvement of Graphene Quality by Electrochemical Exfoliation using Polarity Reversing Potential
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고품질 그래핀의 대량생산은 그래핀의 다양한 응용 분야에서 산업적 활용을 실현하기 위한 핵심 과제로, 이를 목표로 여러 시도가 이루어지고 있다. 본 연구에서는 전기화학 박리 공정에서 전압 인가로 인한 그래핀 품질 저하문제를 해결하면서 높은 수율을 동시에 향상시킬 수 있는 간단한 개선 방안을 제안한다. 전기화학 박리 과정에서 활성 라디칼 및 전해질 이온과의 반응으로 발생하는 그래핀의 산화와 결함 형성을 억제하기 위해, 전압의 극성과 세기를 교대로 변환하는 기술을 도입하고 최적화하였다. 이를 통해 박리된 흑연 표면에 형성된 산소 작용기를 효과적으로 제거함과 동시에 흑연 층간의 이온 삽입 효율을 높였다. 이러한 공정 개선으로 결함 밀도가 낮은 (ID/IG = 0.29) 고순도 (C/O = 12.72) 그래핀을 생산할 수 있었다. 또한, 기존 공정에 비해 63% 더 큰 크기와 26% 더 얇은 두께를 나타내어 그래핀의 구조적 우수성을 확인하였다. 전기화학적 특성 평가 결과, 비정전용량이 103.5 F g–1로 40% 향상되었으며, 이를 통해 전기화학적 성능의 큰 개선을 입증하였다.
Abstract
In this study, we present a straightforward yet effective enhancement to the electrochemical exfoliation process, addressing graphene quality degradation caused by prolonged voltage application while ensuring a high yield. To minimize oxidation and defect formation resulting from interactions with active radicals and electrolyte ions during exfoliation, we implemented polarity-reversing potential technique with alternating voltage. This approach effectively removed oxygen functional groups from the exfoliated graphite surface while enabling efficient ion intercalation between graphite layers. As a result of this improved process, graphene with low defect density (ID/IG = 0.29) and high purity (C/O = 12.72) was successfully produced. Additionally, the graphene exhibited a 63% larger lateral size and 26% reduced thickness compared to conventional methods, highlighting its superior structural properties. Electrochemical performance evaluations further demonstrated a specific capacitance of 103.5 F g–1, —representing a 40% improvement — confirming significant enhancements in electrochemical performance.
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